PORTLAND – The head of the Department of Homeland Security toured the port of Portland on Tuesday as part of a two-day visit to learn more about border security challenges in Maine.

Secretary Michael Chertoff took a tour of Portland Harbor in a Coast Guard patrol boat and visited the port’s emergency operations center with U.S. Sen. Susan Collins, R-Maine, who invited Chertoff to the state. His visit comes as Congress considers how best to allocate Homeland Security grants among states.

Today, Chertoff is scheduled to be in northern Maine to view the U.S.-Canadian border by helicopter and meet with border security officials in Houlton.

Collins, who chairs the Senate Homeland Security Committee, said she wanted Chertoff to come to Maine to get a firsthand glimpse of the issues affecting Maine ports and land borders. Port security can stand to be improved in many ways, she said, and deserves high priority.

“It’s so much easier to secure an airport than a seaport,” Collins said at a news conference on the Portland waterfront.

Maine’s 611-mile border with Canada comprises rugged mountains, thick forests, lakes, rivers, fields and ocean. People cross illegally in cars and trucks, on foot and on snowshoes, in powerboats and canoes, on all-terrain vehicles and snowmobiles. For as long as anyone can remember, smugglers have crossed back and forth with drugs, liquor and cigarettes.

And even with border agents using four-wheel-drive vehicles, ATVs, snowmobiles and boats, along with cameras and motion sensors, it’s impossible to protect the border 100 percent.

Chertoff’s visit to Maine comes as lawmakers debate how best to divvy up Homeland Security funds to states.

Collins last month succeeded in adding an amendment to the Senate version of the DHS annual spending bill that would guarantee minimum Homeland Security grants for emergency first responders in rural states.

Under her provision, Maine would get more than twice as much next year as it would have from a competing proposal favored by President Bush. The Senate version still must be reconciled with a House version that guarantees small states less than half as much money.

Collins said her provision strikes the right balance by allocating money based on risk while also guaranteeing a minimum for states such as Maine.

But critics have said that Collins’ amendment would take scarce Homeland Security money away from at-risk states to give to rural areas with little threat of terrorism.

On Tuesday, Chertoff said his department must address a “whole menu” of challenges when deciding how best to evaluate and minimize risk.

Portland’s port has multiple roles in commerce, transportation and recreation, and the activities have far-reaching effects. For instance, Chertoff said, the port’s oil terminals provide fuel and heating sources throughout the Northeast, not just Maine.

Chertoff said he favors a risk-based system when allocating money, but there shouldn’t be a state-vs.-state competition for security dollars, he said. Rather, “it’s a matter of maximizing security of the country.”

“When we look at risks we don’t just look at jurisdictional boundaries,” he said.